In recent years there has been a greater demand for compact electronic devices which feature higher performance. In particular, studies have been conducted on increasing the speed of signal transmission paths within electronic devices by connecting electronic components with optical signals in order to increase signal transmission rates, and optical waveguides have attracted attention as optical transmission media for that purpose. Optical waveguides encompass a first medium which is essentially transparent to the light of the optical frequency carrier waves and a second medium having a lower refractive index than that of the first medium. The first medium is surrounded by, or otherwise enclosed within, the second medium. Light introduced into an end of the first medium undergoes total internal reflection at the boundary with the second medium and thus is guided along an axis of the first medium. Perhaps the most frequently used optical transport medium is glass formed into an elongated fiber.
However, while glass optical fibers are convenient for data transfer over long distances, they are inconvenient for complex high-density circuitry because the high density of such circuitry makes their use problematic and expensive. Polymeric materials, on the other hand, hold great promise for constructing cost effective, reliable, passive and active integrated components capable of performing the required functions for integrated optics.
Therefore, considerable effort has been directed to forming optical coupling devices and more recently to optical waveguides that can be formed of polymeric materials using photohardenable techniques. For example, U.S. Pat. Nos. 5,292,620; and 7,820,356 disclose forming certain of such waveguide structures having a predetermined geometry.
There are also other techniques used in forming optical waveguides using organic polymeric materials. For example, Japanese laid-open patent publications Nos. JP 2004-35838 H10-48443 and JP 2001-296438 disclose a method of exposing a polymer film to an actinic radiation to change the chemical structure of the polymer so as to obtain a waveguide structure.
Similarly, Japanese laid-open patent publication Nos. JP 2005-283840 and JP 2010-90328 disclose certain photosensitive resin compositions useful for the formation of an optical waveguide. However, methods disclosed therein for the fabrication of the optical waveguide appears to be complicated, and there appears to be further need for developing better polymeric compositions that are capable of providing better transmission properties, compact size and higher performance of electronic devices.